Fire-bridge of marine-boiler and other furnaces.



F. J. BLAKE & B. J. CALDWELL.

FIRE mums 0F MARINE BOILER AND OTHER FURNACES.

APPLICATION FILED APB.8, 1913. Llliglggfl I Patented Jan.5,1915.'

3 SHEETS-SHEET 1.

"H5 Il-URPIfi PETERS (:0 PHOTO-LITHQ, WASHING TON, r)

P. J. BLAKE & R. J. CALDWELL.

FIRE BRIDGE OF MARINE BOILER AND OTHER FURNACES.

APPLICATION FILED APR. 8, 1913.

1, 1 24, 1 02,, Patented Jan. 5, 1915.

3 SHEETS-SHEET 2.

.25 1 y 38 #13; J4 I 3 A 44 2? J7 F /30 48 I32 1:111": 25

HE NORRIS PETERS c0. PHOTO LITHO.. WASHINGTON. n c.

P. J. BLAKE & R. J. CALDWELL.

FIRE BRIDGE OF MARINE BOILER AND OTHER FURNACES.

APPLIGATION FILED APILB, 1913..

1,,124J02, Patented Jan.5,1915.

s SHEETSSHEET a.

N NORRIS PETERS co PHGTO-LITHn. wasmwcmn L UNITED STATES PAE T FTQE.

FREDERICK JOHN BLAKE, OF BASSET'I, AND ROBERT JOHN CALDYVELL, OF SOUTH- AMPTON, ENGLAND.

FIRE-BRIDGE 0F MARINE-BOILER AND OTHER FURNACES.

Application filed April 8, 1913.

To all whom it may concern Be it known that we, FREDERICK JOHN BLAKE and ROBERT JOHN CALDWELL, both subjects of the King of Great Britain, residing, respectively, at Beechcroft, Burgess street, Bassett, in the county of Hampshire, England, and 63 Wilton avenue, Southampton, in the county of Hampshire, England, have invented certain new and useful Improvements in and relating to Fire-Bridges of Marine-Boiler and other Furnaces, of which the following is a specification.

This invention relates to hollow firebridges for marine boiler and other furnaces, of the kind in which air from the ashpit is allowed to pass into the firebridge and thence to the furnace through an inclined grid or auxiliary grate consisting of a number of independent bars comprising the top or front of the hollow firebridge. Hitherto the auxiliary firebars of such firebridges have been locked down at one end only, the other end resting freely on a bearer or on the main firebars. These firebridges present the defect that the auxiliary firebars can be lifted or otherwise displaced accidentally when in use. Moreover when the auxiliary firebars rest on the main firebars, the main firebars cannot be renewed without first removing the auxiliary firebars. Hollow firebridges are also known in which the auxiliary firebars are held in position by the weight of the main firebars resting on the ends of the said auxiliary firebars. These firebridges present the defect that the auxiliary firebars cannot be replaced without disturbing the main firebars, and also that if a main firebar is burned away or broken when in use and displaced from its position on the corresponding auxiliary firebar, the auxiliary firebar will easily become displaced also.

According to the present invention each inclined auxiliary firebar is securely locked at both ends in the bearer and remains securely locked at both ends in its position when the main firebars are removed. Hence the auxiliary firebars cannot be lifted or displaced accidentally when in use, but if burnt away or broken can be replaced easily, without disturbing the main firebars, and also the main firebars can be renewed without disturbing the auxiliary firebars.

The accompanying drawings show by way of example difierent arrangements by which Specification of Letters Patent.

Patented Jan. 5, 1915.

Serial No. 759,727.

the said invention may be conveniently and advantageously carried into practice.

In these drawings :Figure l is a transverse section of the firebridge on line II of Figs. 2 and 3. Fig. 2 is a front elevation of the firebridge, in position in a flue, with a number of bars removed and the bearer partly shown in section on line II-II of Fig. 1; Fig. 8 is a plan of the firebridge with all the auxiliary firebars removed. Figs. 1, 2 and 3 refer to one form of firebridge constructed according to our invention. A slightly modified form and arrangement of the various parts of the firebridge is shown in Figs. 4, 5, 6 and 7. Fig. 4 is a transverse section of the firebridge on line IVIV of Figs. 5, 6 and 7. Fig. 5 is a front elevation of the auxiliary firebars and part of the side walls of the hollow bearer. Fig. 6 is a front elevation of part of the hollow bearer with the auxiliary firebars removed. Fig. 7 is a plan of part of the hollow bearer with the auxiliary firebars removed. Another slightly modified form and arrangement of the various parts of the firebridge is shown in Figs. 8 and 9. Fig. 8 is a transverse section of the firebridge on line VIIIVIII of Fig. 9. Fig. 9 is a plan of half of the firebridge with the auxiliary firebars removed.

According to the arrangement for carry ing out the invention shown in Figs. 1, 2 and 3, the main firebars 1 are carried on a hollow back bearer comprising a perforated base 2, a front wall 3, a rear wall 4, side walls 5, and webs or stiffeners 6, connecting the front and rear walls. The said hollow back bearer is bolted at the back to achair plate 7 of the usual type, resting on the flue 8, and is supported at its sides by the projecting ends 9 of the base 2, the said ends 9 resting on the curved sides of the flue and being shaped to fit into the corrugations therein.

The back bearer supports the back plate 10 of the furnace. and the auxiliary firebars 11, as well as the main firebars 1. The back plate of the furnace is not an essential part of this invention but inasmuch as it is in common use in the furnaces of marine and other boilers, provision is usually made to support it either on the chair plate or on the bearer of the firebridge. The back plate is intended to deflect the products of combustion passing over the bridge'up the flue,

and to prevent the accumulation of ashes and clinker in the dead space behind the chair plate, such ashes and clinker being commonly carried over the bridge by the draft and pushed over by the firemens rakes. In natural draft furnaces provision is sometimes made for the supply of extra air behind the firebridge when desired, this being effected bv means of a suitable valve in the chair plate and perforations in the back plate. Such provision may be made in back plates intended for use in conjunction with our invention but in the case of forced draft furnaces it is usually not required. The back plate is preferably faced on the upper side with firebricks and clay.

The back bearer may be cast in one piece or may be made up of a number of transversely divided sections bolted together. In Figs. 1, 2 and 3 a bearer cast in two equal sections is shown. In order to join these sections together the abutting ends are each provided with a web 6, having a downward extension 12, and an upward extension 13, the said extended webs being fixed together by bolts 14 and 15. The rear wall 4 of the bearer is turned forward at the top to form a hook or lip 16 which supports the ends of the auxiliary bars 11 and, by engaging with the lugs 17, prevents the auxiliary firebars from being lifted out of place at their upper ends. The lower or front ends of the auxiliary firebars 11 rest on the front wall 3 of the bearer and are prevented from sliding forward and from being lifted out by the lugs 18 which bear against the front wall 3. In order to introduce the auxiliary firebars into the bridge a gap 19 is provided in the lip 16 on the rear wall 4 sufficiently wide to allow the lugs 1.7 on the auxiliary firebars to pass through so that the auxiliary fire: bars may be dropped on to their supporting walls at this gap and slid along into place after the lugs 17 have been engaged under the lip 16.

In Fig. 3 the gap 19 is shown at the middle of the bridge and is sufiiciently wide to pass in only one bar at a time. The gap may however be made wide enough to pass in several bars at one time and may be situated at any desired position in the rear wall. The auxiliary bar 20 which is introduced last remains over the gap 19 in the lip 16 so that this auxiliary firebar is not locked down at its upper end. The bar 20 is made a little wider than the remaining auxiliary firebars and the lug 17 is cast solid with the end of the bar so that the said bar is a tight fit into the gap 19 and is not easily displaced by accident.

The auxiliary firebars are provided with spacing strips or thickened ends 21 and spacing strips 22. Air from the ashpit 23 passes through the ports 24 in the base of the bearer into the space immediately beneath the auxiliary firebars. Part of the air current passes out through the slots 25 between the bars and between the spacing strips 21 and 22, and assists in completing the combustion of the fuel. The remainder of the air current passes out of the slots 26 at the apex of the bridge, above the spacing strips 22, and serves to complete the com bustion of smoke and combustible gaseous products from the fire.

The thickness of the spacing strips which governs the width of the slots between the bars is such that sufiicient air can pass through the bridge to complete the combustion and to keep the auxiliary firebars below the fusing temperature of the ash or clinker from the fuel so that the clinker does not stick to the bridge but falls down between the auxiliary firebars through the ports 24 into the ashpit 23.

The spacing strips 21, 22 on the auxiliary firebars shown in Fig. 3 are of uniform width but this is not an essential feature of the invention as the slots between the auxiliary firebars may be made of varying width if desired. The auxiliary firebars 11 are a slack fit between the front wall 3 and the lip 16 on the rear wall. 4 so that they may expand freely when heated and also that when cold they may be disengaged from the bearer by slightly inclining sidewise in the plane of the auxiliary grate until the lugs 17 are clear of the lip 16. It is only possible to engage or disengage part of the auxiliary firebars in this way since several bars must be removed before there is space to incline sidewise the remainder sufiiciently to disengage the lugs 17 from the lip 16.

The last few bars must therefore be introduced at the gap 19 as already described. The spaces 27 between the side walls 5 of the bearer and the flue 8 may be left open olr may be conveniently filled in with firec ay.

According to the slightly modified method of carrying out the invention shown in Figs. 4, 5, 6 and 7, the hollow back bearer comprising a perforated base 28, a front wall 29, a rear wall 30, side walls 31 and webs or stifieners 32, has the rear wall 30 diminished in height and slightly advanced as shown at 33 over the whole or only part of its length. The auxiliary firebars 34, which are used in conjunction with the diminished rear wall 33, 'are provided with spacing strips 35, 36 and lugs 37 engaging with front wall 29 as before described. The upper lug 38 on these firebars is slightly modified so as to be fiat on the lower side where it rests on the horizontal top 39 of the diminished wall 33. The said firebars 34 are laid in position in the bridge and afterward locked down by the hook plate 40 which is fastened to the diminished wall 33 by bolts 41.

In Figs. 6 and 7 a bearer cast in three sections is shown. The outer sections have a rear wall and a fixed hook or lip 42 similar to the lip, 16 in Figs. 1, 2, and 3, so that a transverse section of the rear wall on line VV of Figs. 6 and 7 resembles that of the rear wall 4 in Fig. 1. The auxiliary firebars are introduced into the outer sections by inclining or by sliding in from the middle, as already described, before the modified auxiliary firebars are laid in position in the middle sections. The middle section having the diminished rear wall 33, is fixed to the outer sections by bolts 43, 44,- passing through the extended webs 45. In this arrangement the auxiliary firebars in the mid dle of the firebridge and also the hook plate are readily replaced if burned away with out disturbing the remaining parts of the firebridge. Although the diminished rear wall 33 is shown extending over the middle third of the bridge only, this is not an essential feature of the invention since the bearer may be made in any convenient number of sections and the whole or any fraction of the rear wall may be diminished in height. The corresponding hook plate 40 may also be made in one or more convenient sections as desired.

In order that no more air may pass through the bridge than is necessary to complete the combustion of the fuel, it is convenient to make the apertures 46 between the auxiliary firebars at the sides of the bridge narrower than the apertures 47 at the middle, where combustion is most active. This is effected by suitably proportioning the spacing strips 35, 86. The course of the air current from the ashpit, through the ports 48 in the bearer and the apertures 46, .47 is indicated by the arrows in Fig. 4.

According to the slightly modified method of carrying out the invention shown in Figs. 8 and 9, the hollow back bearer, comprising a perforated base 49, a front wall 50, a rear wall 51, side walls 52, and webs or stiifeners 58, has the front wall recessed on the inner side at 54 to receive the hooks on the auxiliary firebars 56. The auxiliary firebars are provided with lugs 57 at their upper ends engaging under the lip 58 on the rear wall 51.

The hollow bearer may be cast in one piece or in a convenient number of sections. In Fig. 9 one half of a bearer cast in two sections is shown. The side walls 52 are suitably shaped to allow the auxiliary firebars to be introduced at either side of the bridge and slid laterally into place. hen the auxiliary firebars 56 have all been introduced they are kept in position by the shaped plates 59 which fit conformably against the flue and which may be fixed by suitable bolts to the bearer if desired. The spaces under the plates 59 may be filled in with fireclay if desired.

Although for the purpose of illustrating our invention only three ways of carrying the same have been described yet the details of the various parts may be altered or modified to suit varying requirements without in any way departing from the invention.

The auxiliary grate may be made concave or convex by the use of suitably curved auxiliary firebars and the bearer may be curved forward or backward if desired. The improved firebridge may be used in conjunction with main firebars of the usual length to obtain more perfect combustion and hence a higher steaming capacity with the same consumption of fuel or, if economy of fuel is desired, the firebridge may be placed nearer the front of the furnace and used in conjunction with somewhat shorter main firebars than usual. The auxiliary firebars may be advantageously cast in a metal mold which produces a bar of exact shape with a smooth, hard surface. The auxiliary firebars may be cast in pairs or in sets of three or more if desired.

What we claim and desire to secure by Letters Patent of the United States is 1. In a firebridge of the kind referred to, the combination of a hollow back bearer having openings at its bottom, straight inclined firebars having their lower ends resting on top of the front wall of said back bearer, each of said lower ends having a depending projection to engage the rear edge of said front wall and prevent the inclined bars slipping forward or being accidentally lifted, and means for locking the upper ends of the bars to the rear wall of the firebridge, substantially as described.

2. In a firebridge, the combination of a hollow bearer having the rear wall thereof provided with a section of diminished height, a series of inclined firebars constituting a grate, certain of which firebars have their upper ends resting on said section, a removable hook-plate bolted to the bearer to lock said firebars in position, and lugs on the upper ends of the said firebars for engagement with the hook-plate, substantially as described.

In testimony whereof we affix our signatures in presence of two witnesses.

FREDERICK JOHN BLAKE. ROBERT JOHN CALDIVELL. Witnesses J. A. BROOMHEAD, HARVEY J. BAVERSTOOK.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D. 0. 

